The flood was created by God to "cleanse" the world of mankind, which (in God's judgement), had become wicked and therefore a source of disappointment to God. All men, women, children, and babies (except for Noah and his family) were killed by drowning.
A large wooden ship was constructed by Noah, or at least under his direction. The ship was approximately 450 feet long and had stalls and pens sufficient to accommodate every species of bird and land animal now existing. (Some creationists believe that the ark sequestered every species of land animal that ever existed.) Prior to the flood one male and one female of every species was motivated to travel, and did travel, from all over the world to the ark. Although there are thousands of species of present-day birds and land animals, this is the result of diversification; the total number of species at the time of Noah was probably much smaller.
Although there were only eight persons on board to feed and clean up after all the animals, the work load was considerably reduced by the fact that the animals were kept in the dark and therefore entered into a state of hibernation.
The earth's human population and all present-day species of birds and land animals are all descendants of the Noah's ark survivors.
There have been numerous aerial sightings and eyewitness accounts of persons who have actually seen the ark close up on the slopes Mount Ararat in eastern Turkey.
Constructing a wooden ship the size of the ark in times of antiquity would require an enormous expenditure of labor and materials. Where did Noah, by all accounts an ordinary man, obtain the resources?
Wooden ships do not withstand violent wind and wave forces very well, and this is particularly true for large wooden ships. The longest modern wooden ships are about 300 feet long, and require steel reinforcing to prevent breaking up.
The contention that a wooden ship 450 feet long could withstand the catastrophic forces postulated in the creationist scenario has to be met with considerable skepticism.
There are over a hundred thousand separate and distinct species of present day birds and land animals. It would be physically impossible for eight persons (Noah, his wife, his three sons and their wives) to provide for the care and feeding of all the flies, termites, worms, snails, fleas, bats, frogs, spiders, bark beetles, intestinal parasites, etc, etc.
Then of course we have several hundred species of larger animals that require 50 to 100 pounds of fodder per day: hippos, rhinos, buffalo, elephants, horses, cattle, giraffes, elk. moose, etc, etc. (Not to mention the enormous grazing dinosaurs that some creationists believe were sequestered in the ark.)
Many, if not most, plants and/or their seeds will not survive a year under water. Did Noah transplant trees from all over the world into tubs to store in the ark, and if so, how did he manage to acquire them?
Don't forget the meat eating animals. How did Noah acquire the tons of meat required for the diet of all those lions, tigers, hyenas, wolves, etc? (Not to mention Tyranosaurus Rex, Allosaurus, and all the rest!) In order for predatory animals like lions, wolves, etc. to survive, they must be outnumbered by their prey by at least a hundred to one. If each grazing animal and each predatory animal were represented by a single pair, then either all the grazing animals would be immediately eaten, or the predatory animals would starve to death, or both. The only other alternative would be for Noah and his descendants to have enough fresh meat stored to feed generations of lions, tigers, wolves, hyenas, foxes, eagles, hawks, etc. This scenario is totally preposterous!
Many animals require special diets. Koalas eat only eucalyptus leaves. Aphids require fresh plants. How would Noah know about these dietary requirements, and how would he obtain food meeting these requirements?
The logistics of stocking the food and feeding the animals is clearly a complete impossibility for eight persons! Just shoveling out the manure would a total impossibility; tons of food per day necessarily creates tons of manure per day!
Unless all those animals happened to be living in the immediate neighborhood (very unlikely, considering the different habitats of rain forest tree frogs, desert geckos, and polar bears), most of them would have to travel over large distances to get to the ark, a physical impossibility. Besides, what could possibly motivate all those frogs, lizards, snakes, salamanders, dragon flies, spiders, ants, etc to leave their natural habitats and attempt to travel thousands of miles to the ark? How could they possibly make the journey? How would they know how to get there?
The Bible states in Gen 7:4 that the ark was loaded in 7 days. The nine million species of animals extant would would have to board at a rate of 30 animals per second!
The creationist claim that diversification has resulted in present-day species being far more numerous than the number of species in the ark contradicts their claim that evolution of species could not, and did not, ever take place.
Keeping in mind that hibernation is not merely sleep, but rather a state of suspended animation, just keeping an animal in the dark will not cause it to hibernate. Most animals do not hibernate under any conditions, least of all in a ship violently tossed about under catastrophic storm conditions.
How did all the present-day parasites and diseases survive the flood without decimating the host population?
In spite of all the reported sightings of the ark on Mount Ararat, there hasn't been a single set of clear photographs showing the exact location and appearance of the ark. The alleged sightings have never been verified by any reputable organization, such as the National Geographic Society.
Additional information is available in talk.origins faq: Problems with a Global Flood